daemon.c

   1 #include "cache.h"
   2 #include "pkt-line.h"
   3 #include "run-command.h"
   4 #include "strbuf.h"
   5 #include "string-list.h"
   6
   7 #ifndef HOST_NAME_MAX
   8 #define HOST_NAME_MAX 256
   9 #endif
  10
  11 #ifdef NO_INITGROUPS
  12 #define initgroups(x, y) (0) /* nothing */
  13 #endif
  14
  15 static int log_syslog;
  16 static int verbose;
  17 static int reuseaddr;
  18 static int informative_errors;
  19
  20 static const char daemon_usage[] =
  21 "git daemon [--verbose] [--syslog] [--export-all]\n"
  22 "           [--timeout=<n>] [--init-timeout=<n>] [--max-connections=<n>]\n"
  23 "           [--strict-paths] [--base-path=<path>] [--base-path-relaxed]\n"
  24 "           [--user-path | --user-path=<path>]\n"
  25 "           [--interpolated-path=<path>]\n"
  26 "           [--reuseaddr] [--pid-file=<file>]\n"
  27 "           [--(enable|disable|allow-override|forbid-override)=<service>]\n"
  28 "           [--access-hook=<path>]\n"
  29 "           [--inetd | [--listen=<host_or_ipaddr>] [--port=<n>]\n"
  30 "                      [--detach] [--user=<user> [--group=<group>]]\n"
  31 "           [<directory>...]";
  32
  33 /* List of acceptable pathname prefixes */
  34 static const char **ok_paths;
  35 static int strict_paths;
  36
  37 /* If this is set, git-daemon-export-ok is not required */
  38 static int export_all_trees;
  39
  40 /* Take all paths relative to this one if non-NULL */
  41 static const char *base_path;
  42 static const char *interpolated_path;
  43 static int base_path_relaxed;
  44
  45 /* If defined, ~user notation is allowed and the string is inserted
  46  * after ~user/.  E.g. a request to git://host/~alice/frotz would
  47  * go to /home/alice/pub_git/frotz with --user-path=pub_git.
  48  */
  49 static const char *user_path;
  50
  51 /* Timeout, and initial timeout */
  52 static unsigned int timeout;
  53 static unsigned int init_timeout;
  54
  55 struct hostinfo {
  56         struct strbuf hostname;
  57         struct strbuf canon_hostname;
  58         struct strbuf ip_address;
  59         struct strbuf tcp_port;
  60         unsigned int hostname_lookup_done:1;
  61         unsigned int saw_extended_args:1;
  62 };
  63
  64 static void lookup_hostname(struct hostinfo *hi);
  65
  66 static const char *get_canon_hostname(struct hostinfo *hi)
  67 {
  68         lookup_hostname(hi);
  69         return hi->canon_hostname.buf;
  70 }
  71
  72 static const char *get_ip_address(struct hostinfo *hi)
  73 {
  74         lookup_hostname(hi);
  75         return hi->ip_address.buf;
  76 }
  77
  78 static void logreport(int priority, const char *err, va_list params)
  79 {
  80         if (log_syslog) {
  81                 char buf[1024];
  82                 vsnprintf(buf, sizeof(buf), err, params);
  83                 syslog(priority, "%s", buf);
  84         } else {
  85                 /*
  86                  * Since stderr is set to buffered mode, the
  87                  * logging of different processes will not overlap
  88                  * unless they overflow the (rather big) buffers.
  89                  */
  90                 fprintf(stderr, "[%"PRIuMAX"] ", (uintmax_t)getpid());
  91                 vfprintf(stderr, err, params);
  92                 fputc('\n', stderr);
  93                 fflush(stderr);
  94         }
  95 }
  96
  97 __attribute__((format (printf, 1, 2)))
  98 static void logerror(const char *err, ...)
  99 {
 100         va_list params;
 101         va_start(params, err);
 102         logreport(LOG_ERR, err, params);
 103         va_end(params);
 104 }
 105
 106 __attribute__((format (printf, 1, 2)))
 107 static void loginfo(const char *err, ...)
 108 {
 109         va_list params;
 110         if (!verbose)
 111                 return;
 112         va_start(params, err);
 113         logreport(LOG_INFO, err, params);
 114         va_end(params);
 115 }
 116
 117 static void NORETURN daemon_die(const char *err, va_list params)
 118 {
 119         logreport(LOG_ERR, err, params);
 120         exit(1);
 121 }
 122
 123 struct expand_path_context {
 124         const char *directory;
 125         struct hostinfo *hostinfo;
 126 };
 127
 128 static size_t expand_path(struct strbuf *sb, const char *placeholder, void *ctx)
 129 {
 130         struct expand_path_context *context = ctx;
 131         struct hostinfo *hi = context->hostinfo;
 132
 133         switch (placeholder[0]) {
 134         case 'H':
 135                 strbuf_addbuf(sb, &hi->hostname);
 136                 return 1;
 137         case 'C':
 138                 if (placeholder[1] == 'H') {
 139                         strbuf_addstr(sb, get_canon_hostname(hi));
 140                         return 2;
 141                 }
 142                 break;
 143         case 'I':
 144                 if (placeholder[1] == 'P') {
 145                         strbuf_addstr(sb, get_ip_address(hi));
 146                         return 2;
 147                 }
 148                 break;
 149         case 'P':
 150                 strbuf_addbuf(sb, &hi->tcp_port);
 151                 return 1;
 152         case 'D':
 153                 strbuf_addstr(sb, context->directory);
 154                 return 1;
 155         }
 156         return 0;
 157 }
 158
 159 static const char *path_ok(const char *directory, struct hostinfo *hi)
 160 {
 161         static char rpath[PATH_MAX];
 162         static char interp_path[PATH_MAX];
 163         size_t rlen;
 164         const char *path;
 165         const char *dir;
 166
 167         dir = directory;
 168
 169         if (daemon_avoid_alias(dir)) {
 170                 logerror("'%s': aliased", dir);
 171                 return NULL;
 172         }
 173
 174         if (*dir == '~') {
 175                 if (!user_path) {
 176                         logerror("'%s': User-path not allowed", dir);
 177                         return NULL;
 178                 }
 179                 if (*user_path) {
 180                         /* Got either "~alice" or "~alice/foo";
 181                          * rewrite them to "~alice/%s" or
 182                          * "~alice/%s/foo".
 183                          */
 184                         int namlen, restlen = strlen(dir);
 185                         const char *slash = strchr(dir, '/');
 186                         if (!slash)
 187                                 slash = dir + restlen;
 188                         namlen = slash - dir;
 189                         restlen -= namlen;
 190                         loginfo("userpath <%s>, request <%s>, namlen %d, restlen %d, slash <%s>", user_path, dir, namlen, restlen, slash);
 191                         rlen = snprintf(rpath, sizeof(rpath), "%.*s/%s%.*s",
 192                                         namlen, dir, user_path, restlen, slash);
 193                         if (rlen >= sizeof(rpath)) {
 194                                 logerror("user-path too large: %s", rpath);
 195                                 return NULL;
 196                         }
 197                         dir = rpath;
 198                 }
 199         }
 200         else if (interpolated_path && hi->saw_extended_args) {
 201                 struct strbuf expanded_path = STRBUF_INIT;
 202                 struct expand_path_context context;
 203
 204                 context.directory = directory;
 205                 context.hostinfo = hi;
 206
 207                 if (*dir != '/') {
 208                         /* Allow only absolute */
 209                         logerror("'%s': Non-absolute path denied (interpolated-path active)", dir);
 210                         return NULL;
 211                 }
 212
 213                 strbuf_expand(&expanded_path, interpolated_path,
 214                               expand_path, &context);
 215
 216                 rlen = strlcpy(interp_path, expanded_path.buf,
 217                                sizeof(interp_path));
 218                 if (rlen >= sizeof(interp_path)) {
 219                         logerror("interpolated path too large: %s",
 220                                  interp_path);
 221                         return NULL;
 222                 }
 223
 224                 strbuf_release(&expanded_path);
 225                 loginfo("Interpolated dir '%s'", interp_path);
 226
 227                 dir = interp_path;
 228         }
 229         else if (base_path) {
 230                 if (*dir != '/') {
 231                         /* Allow only absolute */
 232                         logerror("'%s': Non-absolute path denied (base-path active)", dir);
 233                         return NULL;
 234                 }
 235                 rlen = snprintf(rpath, sizeof(rpath), "%s%s", base_path, dir);
 236                 if (rlen >= sizeof(rpath)) {
 237                         logerror("base-path too large: %s", rpath);
 238                         return NULL;
 239                 }
 240                 dir = rpath;
 241         }
 242
 243         path = enter_repo(dir, strict_paths);
 244         if (!path && base_path && base_path_relaxed) {
 245                 /*
 246                  * if we fail and base_path_relaxed is enabled, try without
 247                  * prefixing the base path
 248                  */
 249                 dir = directory;
 250                 path = enter_repo(dir, strict_paths);
 251         }
 252
 253         if (!path) {
 254                 logerror("'%s' does not appear to be a git repository", dir);
 255                 return NULL;
 256         }
 257
 258         if ( ok_paths && *ok_paths ) {
 259                 const char **pp;
 260                 int pathlen = strlen(path);
 261
 262                 /* The validation is done on the paths after enter_repo
 263                  * appends optional {.git,.git/.git} and friends, but
 264                  * it does not use getcwd().  So if your /pub is
 265                  * a symlink to /mnt/pub, you can whitelist /pub and
 266                  * do not have to say /mnt/pub.
 267                  * Do not say /pub/.
 268                  */
 269                 for ( pp = ok_paths ; *pp ; pp++ ) {
 270                         int len = strlen(*pp);
 271                         if (len <= pathlen &&
 272                             !memcmp(*pp, path, len) &&
 273                             (path[len] == '\0' ||
 274                              (!strict_paths && path[len] == '/')))
 275                                 return path;
 276                 }
 277         }
 278         else {
 279                 /* be backwards compatible */
 280                 if (!strict_paths)
 281                         return path;
 282         }
 283
 284         logerror("'%s': not in whitelist", path);
 285         return NULL;            /* Fallthrough. Deny by default */
 286 }
 287
 288 typedef int (*daemon_service_fn)(void);
 289 struct daemon_service {
 290         const char *name;
 291         const char *config_name;
 292         daemon_service_fn fn;
 293         int enabled;
 294         int overridable;
 295 };
 296
 297 static int daemon_error(const char *dir, const char *msg)
 298 {
 299         if (!informative_errors)
 300                 msg = "access denied or repository not exported";
 301         packet_write_fmt(1, "ERR %s: %s", msg, dir);
 302         return -1;
 303 }
 304
 305 static const char *access_hook;
 306
 307 static int run_access_hook(struct daemon_service *service, const char *dir,
 308                            const char *path, struct hostinfo *hi)
 309 {
 310         struct child_process child = CHILD_PROCESS_INIT;
 311         struct strbuf buf = STRBUF_INIT;
 312         const char *argv[8];
 313         const char **arg = argv;
 314         char *eol;
 315         int seen_errors = 0;
 316
 317         *arg++ = access_hook;
 318         *arg++ = service->name;
 319         *arg++ = path;
 320         *arg++ = hi->hostname.buf;
 321         *arg++ = get_canon_hostname(hi);
 322         *arg++ = get_ip_address(hi);
 323         *arg++ = hi->tcp_port.buf;
 324         *arg = NULL;
 325
 326         child.use_shell = 1;
 327         child.argv = argv;
 328         child.no_stdin = 1;
 329         child.no_stderr = 1;
 330         child.out = -1;
 331         if (start_command(&child)) {
 332                 logerror("daemon access hook '%s' failed to start",
 333                          access_hook);
 334                 goto error_return;
 335         }
 336         if (strbuf_read(&buf, child.out, 0) < 0) {
 337                 logerror("failed to read from pipe to daemon access hook '%s'",
 338                          access_hook);
 339                 strbuf_reset(&buf);
 340                 seen_errors = 1;
 341         }
 342         if (close(child.out) < 0) {
 343                 logerror("failed to close pipe to daemon access hook '%s'",
 344                          access_hook);
 345                 seen_errors = 1;
 346         }
 347         if (finish_command(&child))
 348                 seen_errors = 1;
 349
 350         if (!seen_errors) {
 351                 strbuf_release(&buf);
 352                 return 0;
 353         }
 354
 355 error_return:
 356         strbuf_ltrim(&buf);
 357         if (!buf.len)
 358                 strbuf_addstr(&buf, "service rejected");
 359         eol = strchr(buf.buf, '\n');
 360         if (eol)
 361                 *eol = '\0';
 362         errno = EACCES;
 363         daemon_error(dir, buf.buf);
 364         strbuf_release(&buf);
 365         return -1;
 366 }
 367
 368 static int run_service(const char *dir, struct daemon_service *service,
 369                        struct hostinfo *hi)
 370 {
 371         const char *path;
 372         int enabled = service->enabled;
 373         struct strbuf var = STRBUF_INIT;
 374
 375         loginfo("Request %s for '%s'", service->name, dir);
 376
 377         if (!enabled && !service->overridable) {
 378                 logerror("'%s': service not enabled.", service->name);
 379                 errno = EACCES;
 380                 return daemon_error(dir, "service not enabled");
 381         }
 382
 383         if (!(path = path_ok(dir, hi)))
 384                 return daemon_error(dir, "no such repository");
 385
 386         /*
 387          * Security on the cheap.
 388          *
 389          * We want a readable HEAD, usable "objects" directory, and
 390          * a "git-daemon-export-ok" flag that says that the other side
 391          * is ok with us doing this.
 392          *
 393          * path_ok() uses enter_repo() and does whitelist checking.
 394          * We only need to make sure the repository is exported.
 395          */
 396
 397         if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 398                 logerror("'%s': repository not exported.", path);
 399                 errno = EACCES;
 400                 return daemon_error(dir, "repository not exported");
 401         }
 402
 403         if (service->overridable) {
 404                 strbuf_addf(&var, "daemon.%s", service->config_name);
 405                 git_config_get_bool(var.buf, &enabled);
 406                 strbuf_release(&var);
 407         }
 408         if (!enabled) {
 409                 logerror("'%s': service not enabled for '%s'",
 410                          service->name, path);
 411                 errno = EACCES;
 412                 return daemon_error(dir, "service not enabled");
 413         }
 414
 415         /*
 416          * Optionally, a hook can choose to deny access to the
 417          * repository depending on the phase of the moon.
 418          */
 419         if (access_hook && run_access_hook(service, dir, path, hi))
 420                 return -1;
 421
 422         /*
 423          * We'll ignore SIGTERM from now on, we have a
 424          * good client.
 425          */
 426         signal(SIGTERM, SIG_IGN);
 427
 428         return service->fn();
 429 }
 430
 431 static void copy_to_log(int fd)
 432 {
 433         struct strbuf line = STRBUF_INIT;
 434         FILE *fp;
 435
 436         fp = fdopen(fd, "r");
 437         if (fp == NULL) {
 438                 logerror("fdopen of error channel failed");
 439                 close(fd);
 440                 return;
 441         }
 442
 443         while (strbuf_getline_lf(&line, fp) != EOF) {
 444                 logerror("%s", line.buf);
 445                 strbuf_setlen(&line, 0);
 446         }
 447
 448         strbuf_release(&line);
 449         fclose(fp);
 450 }
 451
 452 static int run_service_command(struct child_process *cld)
 453 {
 454         argv_array_push(&cld->args, ".");
 455         cld->git_cmd = 1;
 456         cld->err = -1;
 457         if (start_command(cld))
 458                 return -1;
 459
 460         close(0);
 461         close(1);
 462
 463         copy_to_log(cld->err);
 464
 465         return finish_command(cld);
 466 }
 467
 468 static int upload_pack(void)
 469 {
 470         struct child_process cld = CHILD_PROCESS_INIT;
 471         argv_array_pushl(&cld.args, "upload-pack", "--strict", NULL);
 472         argv_array_pushf(&cld.args, "--timeout=%u", timeout);
 473         return run_service_command(&cld);
 474 }
 475
 476 static int upload_archive(void)
 477 {
 478         struct child_process cld = CHILD_PROCESS_INIT;
 479         argv_array_push(&cld.args, "upload-archive");
 480         return run_service_command(&cld);
 481 }
 482
 483 static int receive_pack(void)
 484 {
 485         struct child_process cld = CHILD_PROCESS_INIT;
 486         argv_array_push(&cld.args, "receive-pack");
 487         return run_service_command(&cld);
 488 }
 489
 490 static struct daemon_service daemon_service[] = {
 491         { "upload-archive", "uploadarch", upload_archive, 0, 1 },
 492         { "upload-pack", "uploadpack", upload_pack, 1, 1 },
 493         { "receive-pack", "receivepack", receive_pack, 0, 1 },
 494 };
 495
 496 static void enable_service(const char *name, int ena)
 497 {
 498         int i;
 499         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 500                 if (!strcmp(daemon_service[i].name, name)) {
 501                         daemon_service[i].enabled = ena;
 502                         return;
 503                 }
 504         }
 505         die("No such service %s", name);
 506 }
 507
 508 static void make_service_overridable(const char *name, int ena)
 509 {
 510         int i;
 511         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 512                 if (!strcmp(daemon_service[i].name, name)) {
 513                         daemon_service[i].overridable = ena;
 514                         return;
 515                 }
 516         }
 517         die("No such service %s", name);
 518 }
 519
 520 static void parse_host_and_port(char *hostport, char **host,
 521         char **port)
 522 {
 523         if (*hostport == '[') {
 524                 char *end;
 525
 526                 end = strchr(hostport, ']');
 527                 if (!end)
 528                         die("Invalid request ('[' without ']')");
 529                 *end = '\0';
 530                 *host = hostport + 1;
 531                 if (!end[1])
 532                         *port = NULL;
 533                 else if (end[1] == ':')
 534                         *port = end + 2;
 535                 else
 536                         die("Garbage after end of host part");
 537         } else {
 538                 *host = hostport;
 539                 *port = strrchr(hostport, ':');
 540                 if (*port) {
 541                         **port = '\0';
 542                         ++*port;
 543                 }
 544         }
 545 }
 546
 547 /*
 548  * Sanitize a string from the client so that it's OK to be inserted into a
 549  * filesystem path. Specifically, we disallow slashes, runs of "..", and
 550  * trailing and leading dots, which means that the client cannot escape
 551  * our base path via ".." traversal.
 552  */
 553 static void sanitize_client(struct strbuf *out, const char *in)
 554 {
 555         for (; *in; in++) {
 556                 if (*in == '/')
 557                         continue;
 558                 if (*in == '.' && (!out->len || out->buf[out->len - 1] == '.'))
 559                         continue;
 560                 strbuf_addch(out, *in);
 561         }
 562
 563         while (out->len && out->buf[out->len - 1] == '.')
 564                 strbuf_setlen(out, out->len - 1);
 565 }
 566
 567 /*
 568  * Like sanitize_client, but we also perform any canonicalization
 569  * to make life easier on the admin.
 570  */
 571 static void canonicalize_client(struct strbuf *out, const char *in)
 572 {
 573         sanitize_client(out, in);
 574         strbuf_tolower(out);
 575 }
 576
 577 /*
 578  * Read the host as supplied by the client connection.
 579  */
 580 static void parse_host_arg(struct hostinfo *hi, char *extra_args, int buflen)
 581 {
 582         char *val;
 583         int vallen;
 584         char *end = extra_args + buflen;
 585
 586         if (extra_args < end && *extra_args) {
 587                 hi->saw_extended_args = 1;
 588                 if (strncasecmp("host=", extra_args, 5) == 0) {
 589                         val = extra_args + 5;
 590                         vallen = strlen(val) + 1;
 591                         if (*val) {
 592                                 /* Split <host>:<port> at colon. */
 593                                 char *host;
 594                                 char *port;
 595                                 parse_host_and_port(val, &host, &port);
 596                                 if (port)
 597                                         sanitize_client(&hi->tcp_port, port);
 598                                 canonicalize_client(&hi->hostname, host);
 599                                 hi->hostname_lookup_done = 0;
 600                         }
 601
 602                         /* On to the next one */
 603                         extra_args = val + vallen;
 604                 }
 605                 if (extra_args < end && *extra_args)
 606                         die("Invalid request");
 607         }
 608 }
 609
 610 /*
 611  * Locate canonical hostname and its IP address.
 612  */
 613 static void lookup_hostname(struct hostinfo *hi)
 614 {
 615         if (!hi->hostname_lookup_done && hi->hostname.len) {
 616 #ifndef NO_IPV6
 617                 struct addrinfo hints;
 618                 struct addrinfo *ai;
 619                 int gai;
 620                 static char addrbuf[HOST_NAME_MAX + 1];
 621
 622                 memset(&hints, 0, sizeof(hints));
 623                 hints.ai_flags = AI_CANONNAME;
 624
 625                 gai = getaddrinfo(hi->hostname.buf, NULL, &hints, &ai);
 626                 if (!gai) {
 627                         struct sockaddr_in *sin_addr = (void *)ai->ai_addr;
 628
 629                         inet_ntop(AF_INET, &sin_addr->sin_addr,
 630                                   addrbuf, sizeof(addrbuf));
 631                         strbuf_addstr(&hi->ip_address, addrbuf);
 632
 633                         if (ai->ai_canonname)
 634                                 sanitize_client(&hi->canon_hostname,
 635                                                 ai->ai_canonname);
 636                         else
 637                                 strbuf_addbuf(&hi->canon_hostname,
 638                                               &hi->ip_address);
 639
 640                         freeaddrinfo(ai);
 641                 }
 642 #else
 643                 struct hostent *hent;
 644                 struct sockaddr_in sa;
 645                 char **ap;
 646                 static char addrbuf[HOST_NAME_MAX + 1];
 647
 648                 hent = gethostbyname(hi->hostname.buf);
 649                 if (hent) {
 650                         ap = hent->h_addr_list;
 651                         memset(&sa, 0, sizeof sa);
 652                         sa.sin_family = hent->h_addrtype;
 653                         sa.sin_port = htons(0);
 654                         memcpy(&sa.sin_addr, *ap, hent->h_length);
 655
 656                         inet_ntop(hent->h_addrtype, &sa.sin_addr,
 657                                   addrbuf, sizeof(addrbuf));
 658
 659                         sanitize_client(&hi->canon_hostname, hent->h_name);
 660                         strbuf_addstr(&hi->ip_address, addrbuf);
 661                 }
 662 #endif
 663                 hi->hostname_lookup_done = 1;
 664         }
 665 }
 666
 667 static void hostinfo_init(struct hostinfo *hi)
 668 {
 669         memset(hi, 0, sizeof(*hi));
 670         strbuf_init(&hi->hostname, 0);
 671         strbuf_init(&hi->canon_hostname, 0);
 672         strbuf_init(&hi->ip_address, 0);
 673         strbuf_init(&hi->tcp_port, 0);
 674 }
 675
 676 static void hostinfo_clear(struct hostinfo *hi)
 677 {
 678         strbuf_release(&hi->hostname);
 679         strbuf_release(&hi->canon_hostname);
 680         strbuf_release(&hi->ip_address);
 681         strbuf_release(&hi->tcp_port);
 682 }
 683
 684 static void set_keep_alive(int sockfd)
 685 {
 686         int ka = 1;
 687
 688         if (setsockopt(sockfd, SOL_SOCKET, SO_KEEPALIVE, &ka, sizeof(ka)) < 0) {
 689                 if (errno != ENOTSOCK)
 690                         logerror("unable to set SO_KEEPALIVE on socket: %s",
 691                                 strerror(errno));
 692         }
 693 }
 694
 695 static int execute(void)
 696 {
 697         char *line = packet_buffer;
 698         int pktlen, len, i;
 699         char *addr = getenv("REMOTE_ADDR"), *port = getenv("REMOTE_PORT");
 700         struct hostinfo hi;
 701
 702         hostinfo_init(&hi);
 703
 704         if (addr)
 705                 loginfo("Connection from %s:%s", addr, port);
 706
 707         set_keep_alive(0);
 708         alarm(init_timeout ? init_timeout : timeout);
 709         pktlen = packet_read(0, NULL, NULL, packet_buffer, sizeof(packet_buffer), 0);
 710         alarm(0);
 711
 712         len = strlen(line);
 713         if (pktlen != len)
 714                 loginfo("Extended attributes (%d bytes) exist <%.*s>",
 715                         (int) pktlen - len,
 716                         (int) pktlen - len, line + len + 1);
 717         if (len && line[len-1] == '\n') {
 718                 line[--len] = 0;
 719                 pktlen--;
 720         }
 721
 722         if (len != pktlen)
 723                 parse_host_arg(&hi, line + len + 1, pktlen - len - 1);
 724
 725         for (i = 0; i < ARRAY_SIZE(daemon_service); i++) {
 726                 struct daemon_service *s = &(daemon_service[i]);
 727                 const char *arg;
 728
 729                 if (skip_prefix(line, "git-", &arg) &&
 730                     skip_prefix(arg, s->name, &arg) &&
 731                     *arg++ == ' ') {
 732                         /*
 733                          * Note: The directory here is probably context sensitive,
 734                          * and might depend on the actual service being performed.
 735                          */
 736                         int rc = run_service(arg, s, &hi);
 737                         hostinfo_clear(&hi);
 738                         return rc;
 739                 }
 740         }
 741
 742         hostinfo_clear(&hi);
 743         logerror("Protocol error: '%s'", line);
 744         return -1;
 745 }
 746
 747 static int addrcmp(const struct sockaddr_storage *s1,
 748     const struct sockaddr_storage *s2)
 749 {
 750         const struct sockaddr *sa1 = (const struct sockaddr*) s1;
 751         const struct sockaddr *sa2 = (const struct sockaddr*) s2;
 752
 753         if (sa1->sa_family != sa2->sa_family)
 754                 return sa1->sa_family - sa2->sa_family;
 755         if (sa1->sa_family == AF_INET)
 756                 return memcmp(&((struct sockaddr_in *)s1)->sin_addr,
 757                     &((struct sockaddr_in *)s2)->sin_addr,
 758                     sizeof(struct in_addr));
 759 #ifndef NO_IPV6
 760         if (sa1->sa_family == AF_INET6)
 761                 return memcmp(&((struct sockaddr_in6 *)s1)->sin6_addr,
 762                     &((struct sockaddr_in6 *)s2)->sin6_addr,
 763                     sizeof(struct in6_addr));
 764 #endif
 765         return 0;
 766 }
 767
 768 static int max_connections = 32;
 769
 770 static unsigned int live_children;
 771
 772 static struct child {
 773         struct child *next;
 774         struct child_process cld;
 775         struct sockaddr_storage address;
 776 } *firstborn;
 777
 778 static void add_child(struct child_process *cld, struct sockaddr *addr, socklen_t addrlen)
 779 {
 780         struct child *newborn, **cradle;
 781
 782         newborn = xcalloc(1, sizeof(*newborn));
 783         live_children++;
 784         memcpy(&newborn->cld, cld, sizeof(*cld));
 785         memcpy(&newborn->address, addr, addrlen);
 786         for (cradle = &firstborn; *cradle; cradle = &(*cradle)->next)
 787                 if (!addrcmp(&(*cradle)->address, &newborn->address))
 788                         break;
 789         newborn->next = *cradle;
 790         *cradle = newborn;
 791 }
 792
 793 /*
 794  * This gets called if the number of connections grows
 795  * past "max_connections".
 796  *
 797  * We kill the newest connection from a duplicate IP.
 798  */
 799 static void kill_some_child(void)
 800 {
 801         const struct child *blanket, *next;
 802
 803         if (!(blanket = firstborn))
 804                 return;
 805
 806         for (; (next = blanket->next); blanket = next)
 807                 if (!addrcmp(&blanket->address, &next->address)) {
 808                         kill(blanket->cld.pid, SIGTERM);
 809                         break;
 810                 }
 811 }
 812
 813 static void check_dead_children(void)
 814 {
 815         int status;
 816         pid_t pid;
 817
 818         struct child **cradle, *blanket;
 819         for (cradle = &firstborn; (blanket = *cradle);)
 820                 if ((pid = waitpid(blanket->cld.pid, &status, WNOHANG)) > 1) {
 821                         const char *dead = "";
 822                         if (status)
 823                                 dead = " (with error)";
 824                         loginfo("[%"PRIuMAX"] Disconnected%s", (uintmax_t)pid, dead);
 825
 826                         /* remove the child */
 827                         *cradle = blanket->next;
 828                         live_children--;
 829                         child_process_clear(&blanket->cld);
 830                         free(blanket);
 831                 } else
 832                         cradle = &blanket->next;
 833 }
 834
 835 static struct argv_array cld_argv = ARGV_ARRAY_INIT;
 836 static void handle(int incoming, struct sockaddr *addr, socklen_t addrlen)
 837 {
 838         struct child_process cld = CHILD_PROCESS_INIT;
 839
 840         if (max_connections && live_children >= max_connections) {
 841                 kill_some_child();
 842                 sleep(1);  /* give it some time to die */
 843                 check_dead_children();
 844                 if (live_children >= max_connections) {
 845                         close(incoming);
 846                         logerror("Too many children, dropping connection");
 847                         return;
 848                 }
 849         }
 850
 851         if (addr->sa_family == AF_INET) {
 852                 char buf[128] = "";
 853                 struct sockaddr_in *sin_addr = (void *) addr;
 854                 inet_ntop(addr->sa_family, &sin_addr->sin_addr, buf, sizeof(buf));
 855                 argv_array_pushf(&cld.env_array, "REMOTE_ADDR=%s", buf);
 856                 argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 857                                  ntohs(sin_addr->sin_port));
 858 #ifndef NO_IPV6
 859         } else if (addr->sa_family == AF_INET6) {
 860                 char buf[128] = "";
 861                 struct sockaddr_in6 *sin6_addr = (void *) addr;
 862                 inet_ntop(AF_INET6, &sin6_addr->sin6_addr, buf, sizeof(buf));
 863                 argv_array_pushf(&cld.env_array, "REMOTE_ADDR=[%s]", buf);
 864                 argv_array_pushf(&cld.env_array, "REMOTE_PORT=%d",
 865                                  ntohs(sin6_addr->sin6_port));
 866 #endif
 867         }
 868
 869         cld.argv = cld_argv.argv;
 870         cld.in = incoming;
 871         cld.out = dup(incoming);
 872
 873         if (start_command(&cld))
 874                 logerror("unable to fork");
 875         else
 876                 add_child(&cld, addr, addrlen);
 877 }
 878
 879 static void child_handler(int signo)
 880 {
 881         /*
 882          * Otherwise empty handler because systemcalls will get interrupted
 883          * upon signal receipt
 884          * SysV needs the handler to be rearmed
 885          */
 886         signal(SIGCHLD, child_handler);
 887 }
 888
 889 static int set_reuse_addr(int sockfd)
 890 {
 891         int on = 1;
 892
 893         if (!reuseaddr)
 894                 return 0;
 895         return setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR,
 896                           &on, sizeof(on));
 897 }
 898
 899 struct socketlist {
 900         int *list;
 901         size_t nr;
 902         size_t alloc;
 903 };
 904
 905 static const char *ip2str(int family, struct sockaddr *sin, socklen_t len)
 906 {
 907 #ifdef NO_IPV6
 908         static char ip[INET_ADDRSTRLEN];
 909 #else
 910         static char ip[INET6_ADDRSTRLEN];
 911 #endif
 912
 913         switch (family) {
 914 #ifndef NO_IPV6
 915         case AF_INET6:
 916                 inet_ntop(family, &((struct sockaddr_in6*)sin)->sin6_addr, ip, len);
 917                 break;
 918 #endif
 919         case AF_INET:
 920                 inet_ntop(family, &((struct sockaddr_in*)sin)->sin_addr, ip, len);
 921                 break;
 922         default:
 923                 xsnprintf(ip, sizeof(ip), "<unknown>");
 924         }
 925         return ip;
 926 }
 927
 928 #ifndef NO_IPV6
 929
 930 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
 931 {
 932         int socknum = 0;
 933         char pbuf[NI_MAXSERV];
 934         struct addrinfo hints, *ai0, *ai;
 935         int gai;
 936         long flags;
 937
 938         xsnprintf(pbuf, sizeof(pbuf), "%d", listen_port);
 939         memset(&hints, 0, sizeof(hints));
 940         hints.ai_family = AF_UNSPEC;
 941         hints.ai_socktype = SOCK_STREAM;
 942         hints.ai_protocol = IPPROTO_TCP;
 943         hints.ai_flags = AI_PASSIVE;
 944
 945         gai = getaddrinfo(listen_addr, pbuf, &hints, &ai0);
 946         if (gai) {
 947                 logerror("getaddrinfo() for %s failed: %s", listen_addr, gai_strerror(gai));
 948                 return 0;
 949         }
 950
 951         for (ai = ai0; ai; ai = ai->ai_next) {
 952                 int sockfd;
 953
 954                 sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
 955                 if (sockfd < 0)
 956                         continue;
 957                 if (sockfd >= FD_SETSIZE) {
 958                         logerror("Socket descriptor too large");
 959                         close(sockfd);
 960                         continue;
 961                 }
 962
 963 #ifdef IPV6_V6ONLY
 964                 if (ai->ai_family == AF_INET6) {
 965                         int on = 1;
 966                         setsockopt(sockfd, IPPROTO_IPV6, IPV6_V6ONLY,
 967                                    &on, sizeof(on));
 968                         /* Note: error is not fatal */
 969                 }
 970 #endif
 971
 972                 if (set_reuse_addr(sockfd)) {
 973                         logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
 974                         close(sockfd);
 975                         continue;
 976                 }
 977
 978                 set_keep_alive(sockfd);
 979
 980                 if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0) {
 981                         logerror("Could not bind to %s: %s",
 982                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 983                                  strerror(errno));
 984                         close(sockfd);
 985                         continue;       /* not fatal */
 986                 }
 987                 if (listen(sockfd, 5) < 0) {
 988                         logerror("Could not listen to %s: %s",
 989                                  ip2str(ai->ai_family, ai->ai_addr, ai->ai_addrlen),
 990                                  strerror(errno));
 991                         close(sockfd);
 992                         continue;       /* not fatal */
 993                 }
 994
 995                 flags = fcntl(sockfd, F_GETFD, 0);
 996                 if (flags >= 0)
 997                         fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
 998
 999                 ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1000                 socklist->list[socklist->nr++] = sockfd;
1001                 socknum++;
1002         }
1003
1004         freeaddrinfo(ai0);
1005
1006         return socknum;
1007 }
1008
1009 #else /* NO_IPV6 */
1010
1011 static int setup_named_sock(char *listen_addr, int listen_port, struct socketlist *socklist)
1012 {
1013         struct sockaddr_in sin;
1014         int sockfd;
1015         long flags;
1016
1017         memset(&sin, 0, sizeof sin);
1018         sin.sin_family = AF_INET;
1019         sin.sin_port = htons(listen_port);
1020
1021         if (listen_addr) {
1022                 /* Well, host better be an IP address here. */
1023                 if (inet_pton(AF_INET, listen_addr, &sin.sin_addr.s_addr) <= 0)
1024                         return 0;
1025         } else {
1026                 sin.sin_addr.s_addr = htonl(INADDR_ANY);
1027         }
1028
1029         sockfd = socket(AF_INET, SOCK_STREAM, 0);
1030         if (sockfd < 0)
1031                 return 0;
1032
1033         if (set_reuse_addr(sockfd)) {
1034                 logerror("Could not set SO_REUSEADDR: %s", strerror(errno));
1035                 close(sockfd);
1036                 return 0;
1037         }
1038
1039         set_keep_alive(sockfd);
1040
1041         if ( bind(sockfd, (struct sockaddr *)&sin, sizeof sin) < 0 ) {
1042                 logerror("Could not bind to %s: %s",
1043                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1044                          strerror(errno));
1045                 close(sockfd);
1046                 return 0;
1047         }
1048
1049         if (listen(sockfd, 5) < 0) {
1050                 logerror("Could not listen to %s: %s",
1051                          ip2str(AF_INET, (struct sockaddr *)&sin, sizeof(sin)),
1052                          strerror(errno));
1053                 close(sockfd);
1054                 return 0;
1055         }
1056
1057         flags = fcntl(sockfd, F_GETFD, 0);
1058         if (flags >= 0)
1059                 fcntl(sockfd, F_SETFD, flags | FD_CLOEXEC);
1060
1061         ALLOC_GROW(socklist->list, socklist->nr + 1, socklist->alloc);
1062         socklist->list[socklist->nr++] = sockfd;
1063         return 1;
1064 }
1065
1066 #endif
1067
1068 static void socksetup(struct string_list *listen_addr, int listen_port, struct socketlist *socklist)
1069 {
1070         if (!listen_addr->nr)
1071                 setup_named_sock(NULL, listen_port, socklist);
1072         else {
1073                 int i, socknum;
1074                 for (i = 0; i < listen_addr->nr; i++) {
1075                         socknum = setup_named_sock(listen_addr->items[i].string,
1076                                                    listen_port, socklist);
1077
1078                         if (socknum == 0)
1079                                 logerror("unable to allocate any listen sockets for host %s on port %u",
1080                                          listen_addr->items[i].string, listen_port);
1081                 }
1082         }
1083 }
1084
1085 static int service_loop(struct socketlist *socklist)
1086 {
1087         struct pollfd *pfd;
1088         int i;
1089
1090         pfd = xcalloc(socklist->nr, sizeof(struct pollfd));
1091
1092         for (i = 0; i < socklist->nr; i++) {
1093                 pfd[i].fd = socklist->list[i];
1094                 pfd[i].events = POLLIN;
1095         }
1096
1097         signal(SIGCHLD, child_handler);
1098
1099         for (;;) {
1100                 int i;
1101
1102                 check_dead_children();
1103
1104                 if (poll(pfd, socklist->nr, -1) < 0) {
1105                         if (errno != EINTR) {
1106                                 logerror("Poll failed, resuming: %s",
1107                                       strerror(errno));
1108                                 sleep(1);
1109                         }
1110                         continue;
1111                 }
1112
1113                 for (i = 0; i < socklist->nr; i++) {
1114                         if (pfd[i].revents & POLLIN) {
1115                                 union {
1116                                         struct sockaddr sa;
1117                                         struct sockaddr_in sai;
1118 #ifndef NO_IPV6
1119                                         struct sockaddr_in6 sai6;
1120 #endif
1121                                 } ss;
1122                                 socklen_t sslen = sizeof(ss);
1123                                 int incoming = accept(pfd[i].fd, &ss.sa, &sslen);
1124                                 if (incoming < 0) {
1125                                         switch (errno) {
1126                                         case EAGAIN:
1127                                         case EINTR:
1128                                         case ECONNABORTED:
1129                                                 continue;
1130                                         default:
1131                                                 die_errno("accept returned");
1132                                         }
1133                                 }
1134                                 handle(incoming, &ss.sa, sslen);
1135                         }
1136                 }
1137         }
1138 }
1139
1140 #ifdef NO_POSIX_GOODIES
1141
1142 struct credentials;
1143
1144 static void drop_privileges(struct credentials *cred)
1145 {
1146         /* nothing */
1147 }
1148
1149 static struct credentials *prepare_credentials(const char *user_name,
1150     const char *group_name)
1151 {
1152         die("--user not supported on this platform");
1153 }
1154
1155 #else
1156
1157 struct credentials {
1158         struct passwd *pass;
1159         gid_t gid;
1160 };
1161
1162 static void drop_privileges(struct credentials *cred)
1163 {
1164         if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
1165             setgid (cred->gid) || setuid(cred->pass->pw_uid)))
1166                 die("cannot drop privileges");
1167 }
1168
1169 static struct credentials *prepare_credentials(const char *user_name,
1170     const char *group_name)
1171 {
1172         static struct credentials c;
1173
1174         c.pass = getpwnam(user_name);
1175         if (!c.pass)
1176                 die("user not found - %s", user_name);
1177
1178         if (!group_name)
1179                 c.gid = c.pass->pw_gid;
1180         else {
1181                 struct group *group = getgrnam(group_name);
1182                 if (!group)
1183                         die("group not found - %s", group_name);
1184
1185                 c.gid = group->gr_gid;
1186         }
1187
1188         return &c;
1189 }
1190 #endif
1191
1192 static int serve(struct string_list *listen_addr, int listen_port,
1193     struct credentials *cred)
1194 {
1195         struct socketlist socklist = { NULL, 0, 0 };
1196
1197         socksetup(listen_addr, listen_port, &socklist);
1198         if (socklist.nr == 0)
1199                 die("unable to allocate any listen sockets on port %u",
1200                     listen_port);
1201
1202         drop_privileges(cred);
1203
1204         loginfo("Ready to rumble");
1205
1206         return service_loop(&socklist);
1207 }
1208
1209 int cmd_main(int argc, const char **argv)
1210 {
1211         int listen_port = 0;
1212         struct string_list listen_addr = STRING_LIST_INIT_NODUP;
1213         int serve_mode = 0, inetd_mode = 0;
1214         const char *pid_file = NULL, *user_name = NULL, *group_name = NULL;
1215         int detach = 0;
1216         struct credentials *cred = NULL;
1217         int i;
1218
1219         for (i = 1; i < argc; i++) {
1220                 const char *arg = argv[i];
1221                 const char *v;
1222
1223                 if (skip_prefix(arg, "--listen=", &v)) {
1224                         string_list_append(&listen_addr, xstrdup_tolower(v));
1225                         continue;
1226                 }
1227                 if (skip_prefix(arg, "--port=", &v)) {
1228                         char *end;
1229                         unsigned long n;
1230                         n = strtoul(v, &end, 0);
1231                         if (*v && !*end) {
1232                                 listen_port = n;
1233                                 continue;
1234                         }
1235                 }
1236                 if (!strcmp(arg, "--serve")) {
1237                         serve_mode = 1;
1238                         continue;
1239                 }
1240                 if (!strcmp(arg, "--inetd")) {
1241                         inetd_mode = 1;
1242                         log_syslog = 1;
1243                         continue;
1244                 }
1245                 if (!strcmp(arg, "--verbose")) {
1246                         verbose = 1;
1247                         continue;
1248                 }
1249                 if (!strcmp(arg, "--syslog")) {
1250                         log_syslog = 1;
1251                         continue;
1252                 }
1253                 if (!strcmp(arg, "--export-all")) {
1254                         export_all_trees = 1;
1255                         continue;
1256                 }
1257                 if (skip_prefix(arg, "--access-hook=", &v)) {
1258                         access_hook = v;
1259                         continue;
1260                 }
1261                 if (skip_prefix(arg, "--timeout=", &v)) {
1262                         timeout = atoi(v);
1263                         continue;
1264                 }
1265                 if (skip_prefix(arg, "--init-timeout=", &v)) {
1266                         init_timeout = atoi(v);
1267                         continue;
1268                 }
1269                 if (skip_prefix(arg, "--max-connections=", &v)) {
1270                         max_connections = atoi(v);
1271                         if (max_connections < 0)
1272                                 max_connections = 0;            /* unlimited */
1273                         continue;
1274                 }
1275                 if (!strcmp(arg, "--strict-paths")) {
1276                         strict_paths = 1;
1277                         continue;
1278                 }
1279                 if (skip_prefix(arg, "--base-path=", &v)) {
1280                         base_path = v;
1281                         continue;
1282                 }
1283                 if (!strcmp(arg, "--base-path-relaxed")) {
1284                         base_path_relaxed = 1;
1285                         continue;
1286                 }
1287                 if (skip_prefix(arg, "--interpolated-path=", &v)) {
1288                         interpolated_path = v;
1289                         continue;
1290                 }
1291                 if (!strcmp(arg, "--reuseaddr")) {
1292                         reuseaddr = 1;
1293                         continue;
1294                 }
1295                 if (!strcmp(arg, "--user-path")) {
1296                         user_path = "";
1297                         continue;
1298                 }
1299                 if (skip_prefix(arg, "--user-path=", &v)) {
1300                         user_path = v;
1301                         continue;
1302                 }
1303                 if (skip_prefix(arg, "--pid-file=", &v)) {
1304                         pid_file = v;
1305                         continue;
1306                 }
1307                 if (!strcmp(arg, "--detach")) {
1308                         detach = 1;
1309                         log_syslog = 1;
1310                         continue;
1311                 }
1312                 if (skip_prefix(arg, "--user=", &v)) {
1313                         user_name = v;
1314                         continue;
1315                 }
1316                 if (skip_prefix(arg, "--group=", &v)) {
1317                         group_name = v;
1318                         continue;
1319                 }
1320                 if (skip_prefix(arg, "--enable=", &v)) {
1321                         enable_service(v, 1);
1322                         continue;
1323                 }
1324                 if (skip_prefix(arg, "--disable=", &v)) {
1325                         enable_service(v, 0);
1326                         continue;
1327                 }
1328                 if (skip_prefix(arg, "--allow-override=", &v)) {
1329                         make_service_overridable(v, 1);
1330                         continue;
1331                 }
1332                 if (skip_prefix(arg, "--forbid-override=", &v)) {
1333                         make_service_overridable(v, 0);
1334                         continue;
1335                 }
1336                 if (!strcmp(arg, "--informative-errors")) {
1337                         informative_errors = 1;
1338                         continue;
1339                 }
1340                 if (!strcmp(arg, "--no-informative-errors")) {
1341                         informative_errors = 0;
1342                         continue;
1343                 }
1344                 if (!strcmp(arg, "--")) {
1345                         ok_paths = &argv[i+1];
1346                         break;
1347                 } else if (arg[0] != '-') {
1348                         ok_paths = &argv[i];
1349                         break;
1350                 }
1351
1352                 usage(daemon_usage);
1353         }
1354
1355         if (log_syslog) {
1356                 openlog("git-daemon", LOG_PID, LOG_DAEMON);
1357                 set_die_routine(daemon_die);
1358         } else
1359                 /* avoid splitting a message in the middle */
1360                 setvbuf(stderr, NULL, _IOFBF, 4096);
1361
1362         if (inetd_mode && (detach || group_name || user_name))
1363                 die("--detach, --user and --group are incompatible with --inetd");
1364
1365         if (inetd_mode && (listen_port || (listen_addr.nr > 0)))
1366                 die("--listen= and --port= are incompatible with --inetd");
1367         else if (listen_port == 0)
1368                 listen_port = DEFAULT_GIT_PORT;
1369
1370         if (group_name && !user_name)
1371                 die("--group supplied without --user");
1372
1373         if (user_name)
1374                 cred = prepare_credentials(user_name, group_name);
1375
1376         if (strict_paths && (!ok_paths || !*ok_paths))
1377                 die("option --strict-paths requires a whitelist");
1378
1379         if (base_path && !is_directory(base_path))
1380                 die("base-path '%s' does not exist or is not a directory",
1381                     base_path);
1382
1383         if (inetd_mode) {
1384                 if (!freopen("/dev/null", "w", stderr))
1385                         die_errno("failed to redirect stderr to /dev/null");
1386         }
1387
1388         if (inetd_mode || serve_mode)
1389                 return execute();
1390
1391         if (detach) {
1392                 if (daemonize())
1393                         die("--detach not supported on this platform");
1394         }
1395
1396         if (pid_file)
1397                 write_file(pid_file, "%"PRIuMAX, (uintmax_t) getpid());
1398
1399         /* prepare argv for serving-processes */
1400         argv_array_push(&cld_argv, argv[0]); /* git-daemon */
1401         argv_array_push(&cld_argv, "--serve");
1402         for (i = 1; i < argc; ++i)
1403                 argv_array_push(&cld_argv, argv[i]);
1404
1405         return serve(&listen_addr, listen_port, cred);
1406 }